<?php
/**
 * Created by PhpStorm.
 * User: zch
 * Date: 2017/7/20
 * Time: 9:44
 */
require_once __DIR__ . '/Operate.php';

class OperationSub extends Operate
{

    /**
     * OperationSub constructor.
     */
    public function __construct()
    {

    }

    public function getResult()
    {
        return $this->getNumA() - $this->getNumB();
    }
}
